1. Field of the Invention
The present invention relates to a method and package for heating a food product in a microwave oven and in particular to a method and package for microwave heating of a breaded or battered food product.
2. Description of the Prior Art
In recent years, the number of homes containing microwave ovens has grown dramatically. This has resulted in an associated growth in the demand for microwave compatible prepared foods, especially frozen foods such as pies, pizzas, breaded or battered fish fillets, breaded or battered fish sticks, breaded or battered chicken fillets, vegetable and meat tempuras and the like.
However, various problems occur when this type of food product is heated in a microwave oven. Food products such as battered and breaded fish or chicken pieces can contain as much as 80% water. During microwave heating, the water in the product absorbs the bulk of the radio frequency energy causing rapid internal heating of the food product. Under the rapid heating conditions in a microwave oven, the water has a tendency to become vaporized and mobile. In conventional ovens, wherein the food is heated by hot gases within the oven (convection heating) or by heat radiating from the oven heating elements and walls (radiant heating), the surface of the heated food is much hotter than the interior of the food and any water or water vapor reaching the surface of the food will be removed by evaporation or carried away by the warm air flows in the oven, thereby providing the food product surface with a drier "crisp" texture.
However, upon heating moist foods with a breaded or battered coating, in a microwave oven, the interior of the food is raised to a much higher temperature than the surface of the food product, since the surface is exposed to the unheated ambient air in the microwave oven. Accordingly, the water vapor generated in the interior of the food product during microwave heating has a tendency to condense on the cooler breaded or battered surface portion, making it moist and soggy, rather than crisp as in a conventional oven.
In response to these problems, the art has provided vent openings in microwave heating containers so as to facilitate removal of water vapor from the container. Patents which disclosed the use of cartons having vent openings include U.S. Pat. Nos. 4,260,060 to Faller; 4,355,757 to Roccaforte; 4,096,948 to Kuchenbecker; 4,567,341 to Brown; and 4,228,945 to Wysocki.
Elevation of the food product container above the supporting surface of the microwave oven has also been attempted in order to promote venting of water vapor from the food product during microwave heating. Patents describing elevating the food product container above the supporting surface of the microwave oven in order to promote ventilation include U.S. Pat. Nos. 4,260,060 to Faller; 4,355,757 to Roccaforte; 4,096,948 to Kuchenbecker; and 4,228,945 to Wysocki.
Because most microwave heating containers are transparent to microwave energy, they (like the ambient air in the microwave oven) are not heated by the microwave energy and accordingly remain much cooler than the food product during microwave heating. Accordingly, the bottom portions of the food product which are in contact with the cool container remain cooler and have a tendency to absorb condensing water vapor. There have been attempts to minimize the degree of contact between the food product and the bottom of the container in order to prevent the food product from becoming soggy during microwave heating. See for example U.S. Pat. No. 4,355,757 to Roccaforte.
Others have attempted to improve the heating of microwavable food products through the use of a container made with microwave interactive material that converts microwave energy into thermal energy. Typically these containers utilize one or more microwave interactive "heater boards" positioned beneath and/or above the food product. In most cases the food product sits directly on the heater board surface which acts to brown the food product by conduction (i.e., contact) heating. Patents disclosing containers having a microwave interactive layer include U.S. Pat. Nos. 4,555,605 to Brown et al., 4,590,349 to Brown et al., 4,594,492 to Maroszek, and 4,190,757 to Turpin et al.
Unfortunately, these prior art microwave heating containers have not completely eliminated the problem of breaded food product sogginess caused by condensing water vapor during microwave heating. For example, the microwave interactive materials begin to cool immediately after the microwave heating stops. Thus, those parts of the food product which are in contact with the microwave interactive material also begin to cool. Any water vapor in the oven then has a tendency to condense on these cooling parts, leaving them soggy. In addition, these containers sometimes cause overcooking of the parts of the food which are in direct contact with the heater boards. In cases where the container also includes metal-containing microwave shielding for regulating the amount of microwave energy admitted into the container (see for example U.S. Pat. No. 4,190,757), there have been problems with fires caused by microwave arcing.
It is accordingly an object of the invention to provide a microwave heating method and a package assembly which serves as the primary retail package and container for microwave heating of breaded or battered food products, which substantially eliminates the problem of the breaded surface portions becoming soggy, and which provides enhanced crisping of the breaded or battered portions without the attendant problems of overcooking and microwave arcing.
The prior art containers have also suffered from the disadvantage of being difficult to manufacture and/or involve complicated steps for the consumer to follow in order to ready the product for microwave heating.
It is accordingly another object of the present invention to provide a package assembly for a microwave-compatible food product that is easy to manufacture and convenient for the consumer to use.